358 lines
11 KiB
Python
358 lines
11 KiB
Python
"""
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Implementation of the standard :mod:`thread` module that spawns greenlets.
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.. note::
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This module is a helper for :mod:`gevent.monkey` and is not
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intended to be used directly. For spawning greenlets in your
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applications, prefer higher level constructs like
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:class:`gevent.Greenlet` class or :func:`gevent.spawn`.
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"""
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import sys
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__implements__ = [
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'allocate_lock',
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'get_ident',
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'exit',
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'LockType',
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'stack_size',
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'start_new_thread',
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'_local',
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] + ([
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'start_joinable_thread',
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'lock',
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'_ThreadHandle',
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'_make_thread_handle',
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] if sys.version_info[:2] >= (3, 13) else [
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])
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__imports__ = ['error']
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import _thread as __thread__ # pylint:disable=import-error
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__target__ = '_thread'
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__imports__ += [
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'TIMEOUT_MAX',
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'allocate',
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'exit_thread',
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'interrupt_main',
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'start_new'
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]
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# We can't actually produce a value that "may be used
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# to identify this particular thread system-wide", right?
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# Even if we could, I imagine people will want to pass this to
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# non-Python (native) APIs, so we shouldn't mess with it.
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__imports__.append('get_native_id')
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# Added to 3.12
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if hasattr(__thread__, 'daemon_threads_allowed'):
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__imports__.append('daemon_threads_allowed')
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error = __thread__.error
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from gevent._compat import PYPY
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from gevent._util import copy_globals
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from gevent.hub import getcurrent
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from gevent.hub import GreenletExit
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from gevent.hub import sleep
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from gevent._hub_local import get_hub_if_exists
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from gevent.greenlet import Greenlet
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from gevent.lock import BoundedSemaphore
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from gevent.local import local as _local
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from gevent.exceptions import LoopExit
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if hasattr(__thread__, 'RLock'):
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# Added in Python 3.4, backported to PyPy 2.7-7.0
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__imports__.append("RLock")
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if hasattr(__thread__, 'set_name'):
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# Added in Python 3.14
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__imports__.append('set_name')
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def get_ident(gr=None):
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if gr is None:
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gr = getcurrent()
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return id(gr)
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def _start_new_greenlet(function, args=(), kwargs=None):
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if kwargs is not None:
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greenlet = Greenlet.spawn(function, *args, **kwargs) # pylint:disable=not-a-mapping
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else:
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greenlet = Greenlet.spawn(function, *args)
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return greenlet
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def start_new_thread(function, args=(), kwargs=None):
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return get_ident(_start_new_greenlet(function, args, kwargs))
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def start_joinable_thread(function, handle=None, daemon=True): # pylint:disable=unused-argument
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"""
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*For internal use only*: start a new thread.
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Like start_new_thread(), this starts a new thread calling the given function.
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Unlike start_new_thread(), this returns a handle object with methods to join
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or detach the given thread.
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This function is not for third-party code, please use the
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`threading` module instead. During finalization the runtime will not wait for
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the thread to exit if daemon is True. If handle is provided it must be a
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newly created thread._ThreadHandle instance.
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"""
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# The above docstring is from python 3.13.
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#
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# _thread._ThreadHandle has:
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# - readonly property `ident`
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# - method is_done
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# - method join
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# - method _set_done - threading._shutdown calls this
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#
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# I have no idea what it means if you pass a provided handle,
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# because you can't change the ident once created, and
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# the constructor of ThreadHande takes arbitrary positional
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# and keyword arguments, and throws them away. (The ident is set
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# by C code directly accessing internal structure members).
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greenlet = _start_new_greenlet(function) # XXX: Daemon is ignored
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# 3.14 tests require always returning a handle object.
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if handle is None:
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handle = _ThreadHandle()
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elif not isinstance(handle, _ThreadHandle):
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raise AssertionError('Must be a gevent thread handle')
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elif handle._had_greenlet:
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raise RuntimeError('thread already started')
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handle._set_greenlet(greenlet)
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return handle
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class _ThreadHandle:
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# The constructor must accept and ignore all arguments
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# to match the stdlib.
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def __init__(self, *_args, **_kwargs):
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"""Does nothing; ignores args"""
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# Must keep a weak reference to the greenlet
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# to avoid problems managing the _active list of
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# threads, which can sometimes rely on garbage collection.
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# Also, this breaks a cycle.
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_greenlet_ref = None
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# We also need to keep track of whether we were ever
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# actually bound to a greenlet so that our
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# behaviour in 'join' is correct.
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_had_greenlet = False
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def _set_greenlet(self, glet):
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from weakref import ref
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assert glet is not None
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self._greenlet_ref = ref(glet)
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self._had_greenlet = True
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def _get_greenlet(self):
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return (
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self._greenlet_ref()
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if self._greenlet_ref is not None
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else None
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)
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def join(self, timeout=-1):
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# TODO: This is what we patch Thread.join to do on all versions,
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# so there's another implementation in gevent.monkey._patch_thread_common.
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# UNIFY THEM.
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# Python 3.14 makes timeout optional, defaulting to -1;
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# we need that to be None
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timeout = None if timeout == -1 else timeout
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if not self._had_greenlet:
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raise RuntimeError('thread not started')
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glet = self._get_greenlet()
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if glet is not None:
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if glet is getcurrent():
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raise RuntimeError('Cannot join current thread')
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if hasattr(glet, 'join'):
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return glet.join(timeout)
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# working with a raw greenlet. That
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# means it's probably the MainThread, because the main
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# greenlet is always raw. But it could also be a dummy
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from time import time
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end = None
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if timeout:
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end = time() + timeout
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while not self.is_done():
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if end is not None and time() > end:
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return
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sleep(0.001)
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return None
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@property
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def ident(self):
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glet = self._get_greenlet()
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if glet is not None:
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return get_ident(glet)
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return None
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def is_done(self):
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glet = self._get_greenlet()
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if glet is None:
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return True
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return glet.dead
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def _set_done(self, enter_hub=True):
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"""
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Mark the thread as complete.
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This releases our reference (if any) to our greenlet.
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By default, this will bounce back to the hub so that waiters
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in ``join`` can get notified. Set *enter_hub* to false not to
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do this. This private API is tightly coupled to our ``threading``
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implementation.
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"""
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if not self._had_greenlet:
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raise RuntimeError('thread not started')
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self._greenlet_ref = None
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# Let the loop go around so that anyone waiting in
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# join() gets to know about it. This is particularly
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# important during threading/interpreter shutdown.
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if enter_hub:
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sleep(0.001)
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def __repr__(self):
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return '<%s.%s at 0x%x greenlet=%r>' % (
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self.__class__.__module__,
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self.__class__.__name__,
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id(self),
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self._get_greenlet()
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)
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def _make_thread_handle(*_args):
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"""
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Called on 3.13 after forking in the child.
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Takes ``(module, ident)``, returns a handle object
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with that ident.
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"""
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# The argument _should_ be a thread identifier int
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handle = _ThreadHandle()
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handle._set_greenlet(getcurrent())
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return handle
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class LockType(BoundedSemaphore):
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"""
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The basic lock type.
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.. versionchanged:: 24.10.1
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Subclassing this object is no longer allowed. This matches the
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Python 3 API.
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"""
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# Change the ValueError into the appropriate thread error
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# and any other API changes we need to make to match behaviour
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_OVER_RELEASE_ERROR = __thread__.error
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if PYPY:
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_OVER_RELEASE_ERROR = RuntimeError
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_TIMEOUT_MAX = __thread__.TIMEOUT_MAX # pylint:disable=no-member
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def __init__(self):
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"""
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.. versionchanged:: 24.10.1
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No longer accepts arguments to pass to the super class. If you
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want a semaphore with a different count, use a semaphore class directly.
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This matches the Lock API of Python 3
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"""
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super().__init__()
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@classmethod
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def __init_subclass__(cls):
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raise TypeError
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def acquire(self, blocking=True, timeout=-1):
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# This is the Python 3 signature.
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# On Python 2, Lock.acquire has the signature `Lock.acquire([wait])`
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# where `wait` is a boolean that cannot be passed by name, only position.
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# so we're fine to use the Python 3 signature.
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# Transform the default -1 argument into the None that our
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# semaphore implementation expects, and raise the same error
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# the stdlib implementation does.
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if timeout == -1:
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timeout = None
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if not blocking and timeout is not None:
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raise ValueError("can't specify a timeout for a non-blocking call")
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if timeout is not None:
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if timeout < 0:
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# in C: if(timeout < 0 && timeout != -1)
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raise ValueError("timeout value must be strictly positive")
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if timeout > self._TIMEOUT_MAX:
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raise OverflowError('timeout value is too large')
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try:
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acquired = BoundedSemaphore.acquire(self, blocking, timeout)
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except LoopExit:
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# Raised when the semaphore was not trivially ours, and we needed
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# to block. Some other thread presumably owns the semaphore, and there are no greenlets
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# running in this thread to switch to. So the best we can do is
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# release the GIL and try again later.
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if blocking: # pragma: no cover
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raise
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acquired = False
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if not acquired and not blocking and getcurrent() is not get_hub_if_exists():
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# Run other callbacks. This makes spin locks works.
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# We can't do this if we're in the hub, which we could easily be:
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# printing the repr of a thread checks its tstate_lock, and sometimes we
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# print reprs in the hub.
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# See https://github.com/gevent/gevent/issues/1464
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# By using sleep() instead of self.wait(0), we don't force a trip
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# around the event loop *unless* we've been running callbacks for
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# longer than our switch interval.
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sleep()
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return acquired
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# Should we implement _is_owned, at least for Python 2? See notes in
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# monkey.py's patch_existing_locks.
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allocate_lock = lock = LockType
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def exit():
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raise GreenletExit
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if hasattr(__thread__, 'stack_size'):
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_original_stack_size = __thread__.stack_size
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def stack_size(size=None):
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if size is None:
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return _original_stack_size()
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if size > _original_stack_size():
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return _original_stack_size(size)
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# not going to decrease stack_size, because otherwise other
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# greenlets in this thread will suffer
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else:
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__implements__.remove('stack_size')
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__imports__ = copy_globals(__thread__, globals(),
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only_names=__imports__,
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ignore_missing_names=True)
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__all__ = __implements__ + __imports__
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__all__.remove('_local')
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# XXX interrupt_main
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# XXX _count()
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